Instrument for locating defective coils in electric machines



I. B. WEST. I INSTRUMENT FOR LOCATING DEFECTIVE COILS IN ELECTRIC MACHINES.

APPLICATION FILED JULY 25, I9I 7- v Patented 0013.17, 1922..

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KK 55 E a u m J. B. WEST. INSTRUMENT FOR LOCATING DEFECTIVE COILS IN ELECTRIC MACHINES. APPLICATION FILED JULY 25,1917- Lggflflg, Patented Oct. 17,1922.

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IIVVENTOR ATTORNEYS zen of theUnited States, and a resident of --r nssea o 17,1922;

State of New York,

' like characters designate corresponding parts ,stator coils.

. telephone receiver or ot tor, with the current othr 'coil or other co" s ?INT oasters.

some a. weer, or SYRACUSE, new roan, nts'raunnn'r res. Loca'rnre nnrncrrvnco'rns m nnncrnrc meansns. Applicationflld July as, 1917. -8eria1,Iil'oi182,GtLl-.

dication. case any coil or arbitrary group of-colls does not give the same indication as 'any'other normal coil or group, it

is known that defects em'st in the former coil or group of-coils, and in case thetest is first made in a group of coils instead of in single coils, and a defect is found in the group, the exact coil in which'the defect is located can be found by narrowing down the test to less number. of coils. In some instances, as'when testing stator. coils the test is started by including a quarter of the coils or an eighth, or. any other arbitrary number, and when a-det'ect is found in any group the test is narrowed down in said group. In other instances, .as'in the case. ofarmature or rotor coils, the test is made through the com mutator segments. f

If there is a'short'circuit in the coils be:

tween the contacts, less current than normal will pass'through' the indicators and a less indication, as'a lower sound in a telephone receiver or smaller reading on a meter, will be obtained, anclif there is an 0 an or parso tially open circuit, the sound wi be louder than normal, or-the meter will act the same as or in some cases give 'a greater reading 7 than when connected directly in the testing slightly modified form of a testing fork, circuit. v '85 the contiguous part of agenerator being. In Fig. 1,1 have shown an instrument for also-shown as in Fig.1. y testing thecoils of generators connected to Figure 2 is a diagrammatic view illustrating the connection .of the instrument with the coils of a generator. V

Figures 3,.and14. are.respectively, a plan view anda side e ovation of the testing fork, the current indicatoras the ammeter being th To all whom it mayconoem.

Be it known that I, JOHN B. Wear, a citi- Syracuse, in the county of Onondaga and have invented a certain new and useful Instrument for Locating Defective Coils in Electric Machines, of which the following is a specification.

This invention has for its object the production of a method and instrument for locating defective coils of electrical machines, as solenoids, the field windings, and armature coils of generators and motors; and the invention consists in the method and in the novel features hereinafter set forth and claimed.

In describing this invention referencc is had to the accompanying drawings in which in all the views. I

Figure 1 is a diagrammatic View illustrating one form" of my invention, the chan' eover switchbeing arranged to adjust themstrument for use when the feedcurrent is alternating, the contiguous part of a gen-a erator, the armature coilsof which-arejto be tested, being also shown.

Figure 1 i'sadiagrammatic View of a e supplycurrent is direct." .1 and Q'desigomitted. A I nate the lead wires of the testing circuit Figure 5 is a front elevation of ."pa1*ts'seen' which are electrically connected to contacts in Fig. 3; 1 3, 4 ofthe testlng'instrumen't. 1

' .5 and 6 are additional contacts which are connected in circuit with an ammetercarried by the body of theinstrument, {The outside contactsfi, tare insulated fi'om each 31639 other, and are designed to. make contact with test spaced apart commutator scents"? and- My method oftesting 'the'coilsof electric the inner contacts 5, 6 to, make contact with I machines for defects therein as breaks, short .apair of commutator segments located he tween the segments 7 with which the con--, 11% circuits,-etc., includes connecting a testing tacts 3, 4: areengaged. -'l' he instrument A circuit "in series with a coil' or coils, and. is in the form.- of a fork having four fleXihle 7 comparing the currentl bumean'sjofa meter, tines and a handle. The tines or contacts 3,4: heri-current indicaurenormally out' of the plane of the tines or assinfi .through'ganontacts 5, 6 in. order to first engage the comno as a normalcoiis; gmutator segments of a generator, the coils Figure6 is an enlarged fragmentary rear elevation of parts-seen in Fig. 3.

g F Figure 7 is a sectional view on?- i 6. g I V p igure 8 is another form of illustrating the instrumentadapte .toj

-' give substantially the same current i o fiwhich are tested, before the fork is depressed far enough to bring the contacts 5, 6 in engagement with other segments.

-When outside contacts 3, 4 are first brought into engagement with the commuta- 4 with adjacent commutator segments, the ourrent passes through the coils of the meter or through the telephone receiverl, g1v1ng a reading or a sound. As the instrument is jumped quickly from bar to bar around the commutator, if the coils are in perfect condition, the reading or the sound will be substantially the same for each contact.

This reading and sound varies in difi'erent' electric machines. However, if the machine is in substantially perfect condition, the reading or-sound will always be approximately the same in the same machine. If,

however, there is a short circuit, a smaller reading or lower sound than normal will be obtained, as obviously the full current will not pass through the meter or telephone receiver. When .the current indication has a reading or sound which variesfrom normal, the defective coil can be located by shifting the instrument A. Referring to Figure 2, when the outside contacts 3, 4 are first brought into engagement with the commutator sections 7, 7 the current passes from the testing circuit 1, 2 through the outside contacts 3, 4, the commutator segments 7 7 b and the armature coils 8, 9, 10. When the contacts 5, 6 are brought into engagement with the segments 7 7 the current passes through wire ,2, contact 4, segment 7, coil 10, segment 7, contact 6, through the meter or telephone receiver, contact 5, segment 7, coils 8, segment 7?, contact 3, and wire 1. An induced current is also probably generated in the coil 9, which acts on the meter or telephone receiver. Just what the action of the current is is immaterial as the test is made by comparison only. Also it might be that the current from the contact 4 through coil 9 divides part passing through the segment 7 contact 6, the meter or telephone recelver, contact 5, segment 7, then coil 8, segment 7, and contact 3, and part passing through the coil 9 so that the instrument connected to the contacts 5, 6 is in shunt with the coil 9.

However, as the resistance is greater through the coil 9 than through the instrument, it is believed that the greater part of the current passes through the instrument.

The coil 9 is the one under test and if the current indication or if the sound in the in strument .is the same in all coils coming successlvely under test as the instrument is shifted, there is no trouble in the coils. However, if any coil under test is short circuited so that there is less resistance therethrough ductive transformer, the

than in the normal coil, less current will pass through the instrument.

If the coil 9 is broken more current will pass through the instrument.

The contacts 3, 4 are adjustably mounted on bars 12, 13 in order to be'separated to span a greater number of coils, as in some instances it is desirable to have a greater normal current indication as a greater reading or a greater noise. In some types of electric machines as motors or generators in which the coils are of fine wire, lesscurrent indication will be given when the contacts 3, 4 are separated owing to the fact that the resistance in these fine wire coils offsets the secondary current generated by the coil, it

ways in which the windings are of coarse wire, separation of the contacts 3, 4 cutting in a greater number of coils causes a greater number of coils in such primary circuit and hence a greater currentindication is given in the instrument. However, the operation of the instrument is the same at whatever disstances the contacts 3, 4 are separated.

The bars 12,13,are carried by the handle or body of the instrument and are'insulated there from and from each other, and the contacts 3, 4 are here shown formed with bearings 14, 15 slidable on the bars and held in position by set screws 16. The feed wires are con nected to the bars 12, 13 and extend lengthwise of the handle and are connected to the binding devices 17, 18 electrically connected to the bars 12, 13. The tines or contacts 5, 6 are carried by the body or handle and are insulated from each other, and are connected in circuitwith binding devices 19, 20 which make connections with the meter terminals I direct current circuit, and includes a plug 25 for connection to a supply circuit 26, an inrimary winding 28 of which is connectedtot he plug 25, and the secondary winding 29 of which is connected to binding posts 30, 31 or 32, 33 to which the lead wires 1,- 2 are connected. A device for changing the direct to an alternating cur- .rent, and a change-over switch for controlling the passage of current directly through the transformer and the binding posts, or for connecting said device in series with the primary winding 28 of the transformer between the source of direct current and the transformer.

'Whenthe source of sup ly is alternating nati terrupter;

attractsithe interrupter or vibrator 56 'caus-.

member 35,

fore. to 'the joint 50 and then current, the induction coi or transformer then operates on the ordinary transformer.

principle, thus supplying current for testing purposes, The change-over switch as shown in the drawing makes-the necessary connections tochange the direct current supply into altercurrent for testing purposes. The device ior changing the direct current into an alternating current comprises an interrupter whose magnet coils are-connected in series with the transformer or induction coil 28 and when the interrupter is attracted -by its magnet it brings into contact terminals which short circuit the supply current and cut off the current Jt'romv the induction coil 28 or transformer and the magnets of the in- When the current through said magnet is interrupted the interrupter flies back and breaks the short circuited connec- 'tion,'-thus allowing current from the source of supply to again flow through the transformer or induction coil 28 and through the magnets otthe interrupter. In practice this action-is repeated at a rapid rate. A quarter turn'ofthe-change-over switch makes connections to cutout the interrupter from the of s pp y- 1 The switch 34 is provided with two members 35, 36 the member 35 being arranged to connect two conductors 37, 38' directly together when an alternating current is used, and is operated to disconnect the conductors 37, 38 when the switch is operated, and directly connect the conductors 37 39. The member 36 is arranged to connect the conductors 38, 40 when the member 35 connects the conductors 37, 39.

In operation, a ssuming that the feed 'current is alternatin it passes from the plug 25 'to wire 41 to blnding post 42 to joint43, wire44, through the primary coil 28, wire 45 to' the conductor conductor 38, to the binding post 47, wire 48, to the 'plug' 25.-=-:-.

When the feed current is direct, the switch- 34 is operated so that the switch member 35' connects the bars 37 39, and the switch memher 36 connects the bars 38 and-40. Thecuren passes-from the plug 25, wire 48 binding post 47, wire46, conductor 38, switch 'member '36, conductor 40, wire 49, "joint 50, wire51, through the magnet coils 52, wire- 53, post 54, wire 55, conductor 39 to switch rent 1th member 35, conductor, 37, wire 45 through the primary coil 28, wire 44, hind1ngpost'42, wire 41' to the As' soon as themagnet-52 is plug 25. energized it in g the contact 57 thereon to engage the fixed contact-58 so that the-current. passes asbethe-wire ;59instead of through the I coils 52,

induction coil or transformer from the source 37 across the switch to joint 43,

passes through] aces . to the binding'post 6t), interrupter 56,- con- -'tacts 57, 58 to wire 61 to the joint 43, thence to the plug. Assoon as the magnets 52'are deenergized by the-short circuiting of the current throughthe contacts 57, 58 the interrupter retracts and the circuit is again opened at the contacts 57, 58, and the current against passes through the magnet coils 52. In practice this operation repeats at a rapid rate.

The current induced in the secondary coil 29 passes to. the 30, to wire 62, to the binding post 32, .to the lead wire 1 and the instrument, back; through the. lead wire 2 and the binding post 33, the wires 63, to the coil 29. When the lead wires are connected to the binding posts 30, 31 they are disconnected from the posts 32, 33.

The instrument shown in Fig. 1 is pro-- vided with an ammeter, while that shown in Fig. 1 is connected to a telephone receiver of a machine not having a commutator, and

as here shown the contacts .65 and 66 are points having handles, that is, they are awls, the points being insertable through the insulation of the 0011s and into contact therewith, one of these points having an ammeter 67 in series therewith. In making a test on stator coils, the coils are divided arbitrarily into sections, say the person making the test, tests the coils of each quarter of the stator, that is, he places the contact points and 66 far enough apart to span one-fourth of the coils and notes the reading and proceeds to test the next quarter;

If the current indication is the same for all quarters, there is no trouble inthe coils, if at any' particular quarterthe readin is difi'erent, he can gradually bring the points nearer together taking in each time a less number of coils noting the reading until 'by process of elimination the coil is located, .in which there is "a short circuit or other defeet."

By this instrument defective armature or stator coils can be located in a very few minutcs without tearing down the machine.

WhatI claim is:

'1. instrument for testing thecoils of electric machines comprising a body, two pairs of tines carried by the. body and insulated therefrom, a meter instrument car ried by the body and connected in series'with one pair oft'mes, the other pair of tines being connected res ectively in the legs of a testing circuit,isuhstantially as and for the purpose specified.

. 2.. An instrument for testing the coils'or" electric machines comprising a fork having rent indicating means in series with the intermediate tines, and the testing circuit having its branches connected respectivelyto the outside tines, and one pair of tines being resilient and normally arranged with their engaging ends in a different plane from the other pair of tines, substantially as and for the purpose set forth.

3. An instrument for testing the coils of electric machines comprising a fork having two pairs of substantially parallel tines, one pair being located between the other pair, the pair of tines being located in different \parallel planes-when the fork is held in horizontal position and also the tines being located in different vertical planes, one pair of tines being resilient whereby all tines can be brought into the same plane when pressure is applied to the fork, substantially as and for the purpose described.

4. An instrument for testing the coils of electric machines comprising a fork having two pair of tines, one pair being located between the other pair and out of vertical alinement therewith when the fork is held in horizontal position, some of the tines being normally arranged in a different horizontal lane than others, and being resilient wherey the tines are brought into substantially the same plane when pressure is applied to the fork, substantially as and for the purpose specified.

5. An instrument for testingthe coils of electric machines comprising a fork having two pair of tines, one pair being located between the members of the other pair and out of vertical 'alinement therewith when the fork is held in horizontal position, current indicating means connected in series with one pair of tines and a testing circuit having its branches connected respectively to the members ofthe other pair of tines, and the tines being normally arranged in substantial horizontal planes when the fork is held in.

horizontal position and some of the tines being resilient whereby they are all brought into the same plane when pressure is applied to the fork, substantially as and for the purpose set forth'.

6. An instrument for testing coils of elecpurpose set forth.

tric machines comprising a fork including a body, laterally extending conductor bars insulated from each other, a pair of tines mounted on the bars and adjustable laterally thereon, and a second pair of tinesinterposed between the former pair and insulated therefrom and from each other, substantially as and for the purpose specified.

7. An instrument for testing coils of electric machines comprising a fork including a body, laterally extending conductor bars insulated from each other, a pair of tines mounted on the bars and adjustable laterally thereon, and a second pair of tines interposed between the former pair and insulated therefrom and from each other, one pair being resilient and normally having their engaging ends out of the plane of the ends of the other pair, substantially as and for the 8. A testing instrument chines comprising a fork including a handle,

two pairs of tines carried by the handle and insulated from eachv other and from the' handle, one pair being located intermediate of the members of the other pair, and a meter mounted on the handle and connected in series with the members of the intermediate pair, the outer pair being connected to dle and connected in.series with the members of the intermediate pair, the outer pair being connected to the legs of the feed circuit, and being mounted on and adjustable laterally along the bars, substantially as and for the purpose specified.

In testimony v whereof, I have hereunto signed my name at Syracuse, in the county of Onondaga, and State of New York, this 27th day of June, 1917.

JQHN B. WEST. 

